Vehicles may introduce a liquid spray into an airflow of an internal combustion engine for various reasons. For example, diesel engines may employ exhaust aftertreatment systems to reduce gaseous compounds such as nitrogen oxides (NOx). One method involves injecting a reductant, such as an aqueous urea solution, into the exhaust system upstream from a selective catalytic reaction (SCR) catalyst. When injected into the gas flow, urea decomposes to ammonia (NH3), which is captured and stored on a surface of the downstream SCR catalyst. The stored ammonia catalyzes the reduction of NOx to nitrogen (N2) and water (H2O) as the exhaust gas flows through the SCR catalyst. Various systems for ensuring proper mixing of the urea solution with the exhaust gas flow have been proposed.
For example, US2010/0132344 describes a static mixer that allows for mixing of a liquid spray injected within an exhaust gas flow. The static mixer includes a number of guide vane plates that create a number of grating openings arranged in several rows to form a ring shape that fits the geometry of the exhaust pipe. The guide vane plates are tilted, preferably between 40-60 degrees, relative to a plane of the static mixer and project away from the mixer plane.
The inventors herein have recognized various issues with the above system. In particular, the particular geometry of the static mixer relies upon a particular arrangement of the spray nozzle with the exhaust gas flow, such as injecting the liquid spray at a bend of the exhaust pipe. Thus, the liquid spray is injected in line with the exhaust gas flow and the static mixer is positioned downstream from the injector to induce turbulence via the tilted guide vane plates, which leads to mixing of the fluid-spray and the exhaust gas. In general, pipe bends require longer mixing lengths to achieve a spray direction that is coaxial with the exhaust gas flow. Thus, such an arrangement may not be included in smaller vehicle applications where exhaust system size is limited.
As such, one example approach to address the above issues is to provide a fluid-spray atomizer that receives a liquid spray from a non-gas flow direction and redirects the liquid spray to follow a gas flow direction. In this way, it is possible to inject a fluid into an exhaust gas flow, without positioning the fluid-spray atomizer at a pipe bend and/or downstream from the pipe bend. Specifically, the fluid-spray atomizer may include a plurality of horizontal slats, wherein each horizontal slat is in line with the exhaust gas flow direction. Further, each horizontal slat may be a different size in at least one dimension and/or each horizontal slat may have a skewed position with respect to another horizontal slat at an upstream side of the fluid-spray atomizer. This configuration enables droplets from the fluid-spray to be received from the non-gas flow direction. Thus, the fluid-spray atomizer may be suitable for any vehicle application due to the resulting geometric configuration of the fluid-spray atomizer. Therefore, the fluid-spray atomizer may be suitable for any vehicle application due to a compatibility of the fluid-spray atomizer with a variety of different positions/locations and resulting spray target angles. Further, the resulting geometric configuration may reduce fluid-spray droplet size and may disperse the droplets within a mixing region of the exhaust passage.
Note that the horizontal slats may be arranged in any suitable geometry for receiving the fluid-spray and entraining fluid-spray droplets to a downstream side of the fluid-spray atomizer. For example, the horizontal slats may be in a louver configuration, a stacked configuration, a nested configuration, a step-wise configuration, and/or a cascading tier configuration. Further, the particular geometry of the fluid-spray atomizer may be configured to receive any suitable spray footprint in terms of size and/or geometry of the footprint. Further still, the fluid-spray atomizer may be positioned downstream from a pipe bend, if desired.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.